Patent Application
20050191151
The present disclosure relates generally to inhibiting or preventing rotation between threaded components and, more specifically, to anti-rotation apparatus that may be used to inhibit or prevent rotation between an internally threaded component such as an actuator rod and an externally threaded component such as a valve stem extension rod or the like.
Process control plants often employ sliding stem type valves to control the flow of process fluids. A sliding stem valve typically includes a valve stem that extends from the body of the valve and which is coupled to an actuator via a stem connector. In general, the actuator (e.g., a pneumatic, an electric actuator, a hydraulic actuator, etc.) is responsive to a controller to stroke the valve stem (e.g., by moving the valve stem toward/away from the valve body) to vary an amount of fluid flowing through the valve.
In some cases, such as applications involving high temperature environments and applications requiring a bellows to surround the valve stem (e.g., when controlling toxic fluids), the valve and its actuator are separated by a greater distance than used in many other applications. To increase the distance between the valve and the actuator, an extension stem or rod is typically used to couple the valve stem to the actuator. One end of the extension stem or rod is typically coupled to the valve stem using a conventional stem connector. The other end of the extension stem or rod typically includes an externally threaded portion configured to engage with the internal threads of the actuator rod.
To prevent the extension stem from rotating with respect to the actuator rod after installation of the actuator on the valve, a locking mechanism such as one or more lock nuts, lock washers, clamps, etc. may be employed. However, for many applications such as, for example, those involving bellows noted above, only a limited amount of access to the point at which the actuator rod is coupled to the extension stem is provided. As a result, it is often very difficult to access the apparatus used to lock (i.e., prevent rotation of) the actuator rod relative to the extension stem with the tools used to adjust, fix or otherwise effect the locking apparatus.
In one example embodiment, an anti-rotation apparatus includes a first member configured to be disposed within an aperture of an internally threaded component. The first member includes a first end having a recessed portion configured to receive a second member disposed within the aperture of the internally threaded component. The recessed portion of the first member is configured to receive the second member to cause a peripheral portion of the first end of the first member to frictionally engage a surface within the aperture of the internally threaded component.
In another example embodiment, an anti-rotation apparatus includes a substantially cylindrical body configured to be disposed within an internally threaded component. An end of the substantially cylindrical body includes a deformable portion having a reduced wall section thickness and configured to be driven radially outward by an externally threaded component to frictionally engage the internally threaded component.
The example anti-rotation apparatus described herein enable an externally threaded component to be rotably locked to an internally threaded component without having to employ the use of known lock nuts, lock washers, or the like. More specifically, the anti-rotation apparatus described herein may be particularly useful to rotably lock an externally threaded shaft or rod to an internally threaded component such as another shaft, actuator rod, etc. In contrast to known anti-rotation apparatus such as lock nuts and lock washers, the anti-rotation apparatus described herein is disposed within the internally threaded component (i.e., is encased by the internally threaded component) and may be configured to eliminate the need for the tools (e.g., wrenches, screwdrivers, etc.) that are normally needed to rotably lock an internally threaded component to an externally threaded component.
More specifically, as described in greater detail below, the example anti-rotation apparatus includes a first member configured to be disposed within an internally threaded portion of a component and having a recessed portion configured to receive a second member disposed within the internally threaded portion of the component. As an externally threaded component is threaded into the internally threaded portion, the second member is driven against the recessed portion and at least a peripheral portion surrounding the recessed portion is driven against a surface of the internally threaded portion to frictionally engage the surface to inhibit or prevent the rotation of the internally threaded component relative to the externally threaded component.
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If desired, the upper portion 102 of the anti-rotation apparatus 100 may be configured to deform sufficiently so that the anti-rotation apparatus 100 remains captured (i.e., will not fall out and/or cannot be easily removed from the aperture 204) after being used (e.g., deformed) one time. However, the anti-rotation apparatus 100 may alternatively be configured to enable its removal after one or more uses.
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The example anti-rotation apparatus described herein may be made using, for example, one or more metallic materials via any desired fabrication method. For example, the anti-rotation apparatus may be made using metallic material cut from commonly available smooth or threaded bar stock, a cast metal part, a sintered metal material, etc. One particularly useful material may be #316 stainless steel, which is commonly employed for use in making actuator rods, valve stems, etc. Further, to enhance the frictional engagement between the example anti-rotation apparatus described herein and the internally/externally threaded components, similar or identical materials may be used for these parts (i.e., the anti-rotation apparatus and the threaded components) to facilitate galling. Such galling between components made of like materials serves to significantly increase the friction between the components and, thus, the ability of the anti-rotation apparatus to inhibit or prevent rotation between the threaded components.
While the example anti-rotation apparatus described herein are depicted as being substantially cylindrically-shaped, shapes other than cylindrical may also be used. For example, generally polygonal shapes, shapes having a non-circular cross-section, etc. may be used instead. In any case, the shape or geometry of the anti-rotation apparatus is preferably complementary to the aperture into which the anti-rotation apparatus is intended to be disposed so that when the anti-rotation apparatus engages with another member (e.g., an end of a threaded bolt, a spherical member, etc.) a portion of the anti-rotation apparatus is driven radially outward to sufficiently frictionally engage a surface within the aperture.
The example anti-rotation apparatus described herein may be generally applied but may be particularly useful for inhibiting rotation or rotably locking an externally threaded component such as a shaft, a rod, a bolt, etc. to an internally threaded component such as, for example, another shaft or rod. Further, the example anti-rotation apparatus may be installed without requiring any tools such as those used to effect lock nuts and other known locking apparatus. Still further, in contrast to many known locking mechanisms (e.g., lock nuts, washers, etc.), the example anti-rotation apparatus described herein can be released from a substantially rotably locked or frictional engagement condition by rotating one of the threaded components relative to the other threaded component through a relatively small angle. As a result, the example anti-rotation apparatus described herein can substantially rotably lock an externally threaded component to another threaded component and can be easily unlocked or separated because the angle through which the frictional engagement is effective is relatively small (e.g., does not require transition through a large rotational angle under a highly frictional condition as is the case with some known lock nuts, lock washers, etc.)
Although certain apparatus have been described herein, the scope of coverage of this patent is not limited thereto. To the contrary, this patent covers all embodiments fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10790524 | Mar 2004 | US |
| Child | 10851538 | May 2004 | US |
